Electric drives for centrifugal pumps

ABSTRACT

An electric drive for a submergible pump employed in oil production industry has a vertical oil-filled electric motor the lower portion of which is secured to a hydraulic compensator or surge chamber, while the upper portion is secured to a protector; the protector consists of a casing hermetically divided by a diaphragm into inner and outer chambers to be filled with protective liquid; an intermediate shaft is provided for transmitting rotation from the electric motor to the pump, the shaft having a sealing device concentrically disposed within the casing of the protector; a movable portion of the sealing device is fixed in the axial direction relative to a stationary portion of the same by means of a sliding bearing and two ring pivots disposed at both sides of said bearing. A release valve disposed in the casing of the protector is provided for controlling any excessive pressure in the space above the movable portion of the sealing device.

[' Jan. 15, 1974 Primary Examiner-C. J. Husar Att0rney--Holman & Stern v[57] ABSTRACT An electric drive for a submergible pump employed in oilproduction industry has a vertical oil-filled electric motor the lowerportion of which is secured to a hydraulic compensator or surge chamber,while the upper portion is secured to a protector; the protectorconsists of a casing hermetically divided by a diaphragm into inner andouter chambers to be filled with protective liquid; an intermediateshaft is provided for transmitting rotation from the electric motor tothe pump, the shaft having a sealing device concentrically disposedwithin the casing of the protector; a movable portion of the sealingdevice is fixed in the axial direction relative to a stationary portionof the same by means of asliding bearing and two ring pivots disposed atboth sides of said bearing. A release valve ELECTRIC DRIVES FORCENTRIFUGAL PUMPS Inventors: Alexandr Antonovich Bogdanov,

Strastnoi bulvar, 7, kv. 39; Zinaida Sir'afimovna Pomazkova,Starokashirskoe shosse, 2, korpus l2, kv. 96, both of Moscow,

U.S.S.R.

Oct. 13, 1971 Appl. No.: 188,732

References Cited UNITED STATES PATENTS mh "c a "e S LM .m e hF UnitedStates Patent Bognanov et al.

[22] Filed:

disposed in the casing of the protector is provided for controlling anyexcessive pressure in the space above the movable portion of the sealingdevice.

1 Claim, 2 Drawing Figures Arutunoff.....................Arutunoff.,............ Myers Komor....

Sones Sanger ELECTRIC DRIVES FOR CENTRIFUGAL PUMPS BACKGROUND OF THEINVENTION The present invention relates to submergible pumps and, moreparticularly, to electric drives for centrifugal pumps, screw-typepumps, etc. used in oil industry for recovery of petroleum.

DESCRIPTION OF PRIOR ART metically divided by a diaphragm into an innerand outer chambers filled with fluid and an intermediate shaft fortransmitting power from the electric motor to the pump having a packingdevice concentrically arranged with said casing.

In the known oil-filled electric drive the duration of uninterrupted ofoperation of the pump in a well is determined by the reserve ofprotective fluid and its consumption through the packing devices locatedon the shaft of the protector mounted in the casing of the protector.The reliability of operation of the above-said packing devices and thepressure within the casing determine the reliability and service life ofthe electric. drive as a whole. However,.the known electric drive whichis not specifically designed for taking the axial thrusts from the pumpdriven by the electric motor (as in the machine according tov USA.Pat.'- No. 3,475,634, Cl. 310-87) isliable to have a low'reliabilityand a reduced service life due to the absence of special bearings whichwould take the axial thrusts, thus fixing the movable portion of thepacking device relative to its stationary portion located within theprotector casing as well as dueto the fact that the pressure within thespace above the said packing device can exceed'its rated value.

Furthermore, the absence of a device for controlling excessive pressuresin the electric'drive might result in failure of the components of thedrive, primarily of the packing and flexible elements, which occurs bothduring operation-of the pump and in the case of a low external pressure,for example, when withdrawing the submerged unit from. the liquid in thewell.

DESCRIPTION OF THE INVENTION 1 An object of the present invention is toeliminate the These and other objects are attained owing to the factthat a movable portion of the packing device in the electric drive isdisposed in the axial direction relative to a stationary portion thereofdisposed in the protector casing by means of a sliding bearing mountedinto a protector casing and two pivots arranged at both sides of saidbearing, while any excessive pressure in the space above the packingdevice is controlled by a release valve mounted in the protector casing.

The application of the proposed invention prolongs the uninterruptedperiod of operation of the .electric drive between overhauls, andprovides for reliable and proper 'mounting of the pumping equipment of awell and makes it'possibleto avoid failures of the members of theelectric drive in the process of its withdrawal from the well.

BRIEF DESCRIPTION OF DRAWINGS Theinvention will be better understoodfrom a consideration of the following detailed description of oneparticular embodiment of the invention, reference being made to theaccompanying drawings, in which:

FIG. 1 shows diagrammatically oil-filled electric drive for submergiblepumps, partly in section;

FIG. 2 is a sectional view taken along the line 11-11 in FIG. 1. I

DESCRIPTION OF THE EMBODIMENT I The electric drive for submergible pumpscomprises a vertical oil-filled electric motor 1 (FIG. 1), a hydrau--lic compensator or surge chamber 2 connected to the and is separatedfrom the inner space of the electric motor 1 by the flexible diaphragm 4and the seal 5.

The seal 5 is arranged on-the shaft 6 concentrically about the shaft 6and the casing of the protector 3.

Located within the casing of the protector 3 is a valve 7 which admitsfluids from a reservoir in which the vertical motor and pump 16 aresubmerged into the chamber, B after the protective liquid filling thischamber has been expended. Extending along the chamber B and mountedrigidly on an inside wall of the protector 3 is a pipe 8 which serves asa connecting passage be tween the chambers above and above and below thepipe 8 even when the diaphragm bears against the walls of the body ofthe protector 3 as shown by the dotted lines in FIGS. 1 and 2.

. Mounted on the shaft 6 of the protector is a blade wheel 9 employedfor creating a high pressure in the protector. 3. The shaft 6 ofthe'protector is mounted in bearings 10 and 11, fixed in the casing ofthe protector 3 and is provided with two ring pivots l2, 13. The shaft 6of the protector- 3 is connected to the shaft 14 by means of coupling 21of the electric motor I.- A ring pivot 13 bears against the face of thesliding bearing 10 and does not allow the protector shaft to moveupwards thereby providing for the contact in the working pair of theseal and for its reliable operation. Said shaft 6 of the protector isalso connected by coupling 21 to a shaft l5-of a pump 16. A. ring pivot12 by virtue of its location does not allow the shaft 6 to movedownwards-thereby providing for precise mounting of the protector 3, thepump 16 and the oil-filled electric motor 1 and for normal operation ofthe seal 5.

Also mounted on the shaft 15 of the pump 16 is a thrust bearing 17taking the axial load of the pump and a stuffing box 18.

Mounted in the casing of the protector 3 is a valve 19 connecting thechamber B with the ambient medium and releasing the protective fluid andgas from the chamber B of the-protector 3 under the conditions of anexcessive pressure.

Connected to the lower portion of the oil-filled electric motor 1 is asurge chamber-2 with a flexible container 20.

The oil-filled electric drive operates as follows.

The oil-filled electric motor 1, the flexible container 20 of the surgechamber 2 and the chambers A and B of the protector 3 are filled withprotective and lubricating fluid, in which case the diaphragm 4 bearsagainst the inner wall of the protector casing as shown in FIG. 1.

The electric motor 1, the chambers A and B of the protector 3 can befilled with protective fluids either of the same or of differentviscosity.

in the embodiment of the invention under consideration the chamber B isfilled with protective fluid having a high viscosity than that fillingthe chamber A and the electric motor 1. 1

After switching on the electric motor 1 (FIG. 1), rotation istransmitted from the shaft 14 to the protector 3 and then to the shaft15 of the pump 16.

The protective fluids filling the electric motor 1 and the chambers Aand B of the protector 3 are heated and they expand. The increase in thevolume of this fluid in the electric motor 1 and the chamber A is madeup for by the deformation of the flexible container 20 of the surgechamber 2, while 'in the chamber B it is compensated for by the openingof the valve 19, in which case the diaphragm 4 moves from its initialposition, i.e., from the inner wall of the casing of the protector 3,and levels the pressure in the chambers A and B, that is, the pressuresin the spaces under and above the seal 5. The movable portion of theseal rotates together with the shaft 6, thus sliding along itsstationary portion 5a mounted in the casing of the protector 3. Thesliding surface between the movable portion of the seal 5 and thestationary portion 5a thereof is lubricated at the expense of theprotective fluid forced from the chamber A due to the action ofcentrifugal forces and the small excess pressure in the chamber A.

The opening of the valve 19 eliminates the possibility of creating hihgexcessive pressures in the chamber B and the back flow of high-viscosityprotective fluid through the seal 5 from the chamber B into the chamberA, as well as the action of these pressures on the diaphragm 4 of theprotector 3.

During the operation the ring pivot 13 bears upon the face of thebearing and retains the movable portion .of the seal 5 relative to itsstationary portion 5a, thus providing for required values of specificpressure on the contact surfaces of the friction pair of the seal 5 aswell as required consumption of the protective fluid admitted from thechamber A through the seal 5.

The blade wheel 9 rotates together with the shaft 6 of the protector 3,in which case a high pressure is developed in the chamber A whichthrough the diaphragm 4 is transmitted to chamber B. The viscous fluidfilling this chamber is admitted to the thrust bearing 17 and thestuffing box 18.

The consumption of high-viscosity fluid through the stuffing box 18 ofthe pump 16 is far in excess of that of low-viscosity fluid filling theelectric motor 1 and the chamber A through the seal 5, therefore thediaphragm 4 gradually moves to the external walls of the casing 3 due tothe pressure of the column of fluid contained in the well upon theflexible container 20 of the surge chamber 2 as well as the flow of theprotective fluid from the container 20 into the chamber A of theprotector 3. As soon as all the viscous fluid is consumed from thechamber B, well liquids start flowing into the lower portion of thechamber B.

The pipe 8 serves as a connecting valve between the upper and lowerportions of the chamber B when the diaphragm 4 bears against the wallsof the casing of the protector 3 (shown by dotted lines in FIGS. 1, 2).

As the well liquids enter the chamber B, the latter serves as a settlerseparating the reservoir water from the oil, the oil .moving upwards tothe bearing 17.

As the protective fluid flows out from the chamber A, the diaphragm 4begins moving to its initial position owing to the inflow of thereservoir fluids through the valve 7 into the chamber B. The changes inthe volume of the protective fluid during starting and stopping of theelectric drive are made up for by the flexible container, 20 and thediaphragm 4.

Asall the low-viscosity protective fluid filling the flexible container20 and the chamber A is consumed through the seal 5, the cycle ofoperation of the electric drive in the well is over.

The consumption of protective fluid through the seal 5, and therefore,the entire operating cycle of the electric drive in the well depends onthe correct position of the movable portion of the seal 5 mounted on theshaft 6 relative to its stationary portion 50 mounted in the casing ofthe protector 3 and also depends on the pressures acting in the spacesunder and above the seal 5 controlled by the valves 19 and 7 locatedwithin the casing of the protector 3.

After completing the operating cycle and withdrawing the unit from thefluid in the well, the pressure in the inner space of the electric drivefirst drops down rapidly and then starts raising due to the evolution ofthe gas from the protective fluid (this gas in the dissolved stateduring the operation of the pump). The electric drive is under thepressure due to the presence of the dynamic or static level of the fluidin the well. This pressure is transmitted through the flexible container20 and the diaphragm 4 of the protector 3 from the chamber A to thechamber B. The valve 19 opens and the fluid and gas are vented from thechamber B. When the diaphragm 4 bears against the external wall of thecasing of the protector 3 (as shown by the dotted lines in FIGS. 1,2),the chambers A and B are connected through the open seal 5). The valve19 protects the components of the electric drive from damage, inparticular, it protects the flexible container 20 of the surge chamber 2against breaking.

We claim:

1. An electric motor drive for submergible pumps comprising incombination: a vertical oil-filled electric motor; a hydrauliccompensator connected to the lower portion of said electric motor; aprotector connected to the upper portion of said electric motor andincluding a casing, said casing being divided by a flexible diaphragminto inner and outer chambers to be filled with a fluid; a submergiblepump disposed above fixed in an axial direction relative to saidstationary portion which is disposed in said casing of said protector bymeans of a sliding bearing mounted into said casing; two pivots arrangedat both sides of said bearing; a release valve mounted in said casing ofsaid protector and providing for control of any excessive fluidpress'u'rewithin a space above the movable portion of the sealingdevice.

1. An electric motor drive for submergible pumps comprising incombination: a vertical oil-filled electric motor; a hydrauliccompensator connected to the lower portion of said electric motor; aprotector connected to the upper portion of said electric motor andincluding a casing, said casing being divided by a flexible diaphragminto inner and outer chambers to be filled with a fluid; a submergiblepump disposed above said protector having a shaft arranged to besubstantially aligned with a shaft of the electric motor; anintermediate connecting shaft of said protector having one end connectedto said electric motor shaft and the other end connected to the shaft ofthe submergible pump; a sealing device concentrically disposed in thecasing of said protector and having a stationary portion, and a movableportion of said sealing device which is disposed on said shaft of saidprotector and fixed in an axial direction relative to said stationaryportion which is disposed in said casing of said protector by means of asliding bearing mounted into said casing; two pivots arranged at bothsides of said bearing; a release valve mounted in said casing of saidprotector and providing for control of any excessive fluid pressurewithin a space above the movable portion of the sealing device.